The easiest approach regarding rendering would be to have all cards created externally. So you'd just have to set the right texture rect, but this will be quite static if you try to balance things, since you'd have to edit each card externally.
Instead you could just have textures of the backgrounds and shapes. Then you could draw things on top of each other and apply the text manually, thus allowing you to connect the stats at runtime and change it rather easily, without having to edit the cards and possibly missing that once card game stats got changed but the image itself hasn't.
Of course if you render everything on your own, you'll have to do your own math on how big the text box will be etc.
As an optimization it might be useful to prepare cards when starting the game, thus rendering things to a render texture and then using texture rects to select the right cards.
Also keep in mind before you start implementing the visual side of the game, you should work out the back-end, because that's most likely the more difficult part after all.